Electronic structure and stability of intermetallic compounds in the Ti–Ni System

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1999-12, Vol.273, p.166-169
• Main Authors: Fukuda, T, Kakeshita, T, Houjoh, H, Shiraishi, S, Saburi, T
• Format: Article
• Language: English
• Subjects: Electronic structure calculations; Ni–Ti alloys; Phase stability
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(99)00283-X

For the systematical understanding of the stability of martensitic phases and precipitates which appear in Ti–Ni shape memory alloys, we made a first principle electronic structure calculation of them by using the tight-binding linear muffin-tin orbital method in the atomic sphere approximation (TB-LMTO-ASA). The obtained results are the following: (1)the total electronic density of state (DOS) at the Fermi energy D( ε F) of TiNi decreases as the successive B2→R→B19′ transformation proceeds; (2) when the number of valence electrons increases, D( ε F) of the R-phase increases but that of the B19-phase decreases; (3) D( ε F) of Ti 3Ni 4 decreases as the number of valence electrons decreases and that of TiNi 2 decreases as the number of valence electrons increases. By comparing these results with experimentally obtained results, we derived a criterion that phases appearing in Ti–Ni system tend to become stable at 0 K as D( ε F) decreases.